Study Of The Multi-bar Warp Knitting Machine Based On AC Servo System Controlled By Single-Chip Microcomputer

This paper, by analyzing the executive device and its moving system of the traditional mechanical multi-bar warp knitting machine, and then considering a series of shortcomings of the executive device such as requiring high machining accuracy, perplexing structures, and so on, and combining the weaving process, develops a mechanical drive system based on the ball screw, a high precision absolute position sensor system and AC servo control system of the multi-bar warp knitting machine based on microcomputer control technique, a control system with such functions as continuous working as soon as switching on again and the compatibility with the software data format of the existing design, and a sensor system based on Hall effect sensor for harmonizing the action instruction of the whole system. And this paper also makes use of the serial communication technology between PC and Single-Chip Microcomputer to develop the design data online transmission, which is needed knitting. As a result, the intellectualized degree of the whole system is improved greatly.In this paper, the control system is based on Single-Chip Microcomputer AT89C51, and extends the interface circuits of the external data memory, external I/O ports and so on. And this paper also designs the interface circuits between Single-Chip Microcomputer and the absolute encoder, the programmable watchdog X25045, the Hall effect sensor, the keyboard and LED display, and the serial communication between PC and Single-Chip Microcomputer through RS232C, etc.This paper uses a kind of closed loop system composed of the AC servomotor with a feedback of absolute encoder to drive the ball screw to bring the transmission of movement into effect. As a result of the high efficiency and satisfying synchronism of the ball screw, the system makes a clean sweep of the resistance the return spring forcing on the motion mechanism (The traditional mechanical multi-bar warp knitting machine merely depends on the return spring to realize the bars to move backwards and forwards), and reduces the abrasion of the mechanism greatly. At the same time, in virtue of the feedback of the absolute encoder on the position, the system is able to effectively compensate the overshoot or lost step of the servomotor, namelyaccurately locating the position of the servomotor, and then accurately locating the position of the bars. The system uses the Hall effect sensor to send signal to control the servomotor. Single-Chip Microcomputer will send pulse instruction to drive the servomotor as soon as it receives the signal from the movement detecting system. And then the servomotor will drive the bars and the bars will move in the light of the time series. With the help of RS232C, the serial communication between PC (the host computer) and each Single-Chip Microcomputer (the slave computer) is carried out successfully. And thus, the design data online transmission from PC (the host computer) to each Single-Chip Microcomputer (the slave computer) is also achieved successfully. As a result, the intellectualized degree of the whole system is improved greatly.In this paper, all of the software for controlling is developed with assembly language. The software for communication run in PC (the host computer) is developed with Visual Basic 6.0 to design the serial communication interface, which is a kind of programming language with a friendly programming interface. The results of the tests show that the control system has the following advantages such as high reliability, high control accuracy, high stability, high-intellectualized degree, and so on. And to some extent, the ratio of capability to price is high, too.